The present invention relates to the prevention and treatment of disease by administration of an isolated DNA molecule comprising a gene encoding a protein having glycosyltransferase activity to a cell. In one embodiment of the present invention, a method of treating brain cancer is provided in which a tumor cell is transfected with a DNA molecule that encodes a protein having glycosyltransferase activity resulting in inhibition of the growth or function of that cell.
Cell surface glycoproteins and glycosphingolipids appear to play an important role in a diverse array of cellular functions including regulation of cell growth, differentiation and intercellular communication (Moskal, 1987; Hakomori, 1981). Glycosylation is known to play various roles in host cell-viral interactions, immune cell recognition and migration, neural cell adhesion and function and the function of gonadotropic hormones (Rademacher, 1988). A defect in the glycosyltransferase function has been associated with several inherited diseases. Congenital dyserythropoietic disease, a condition in which abnormal morphologies are detected in various immune cells is observed, has been attributed to a deficiency of GlcNAc transferase II (Fukuda, et al. 1987. J. Biol. Chem. 262:7195-7206). I-cell disease and pseudo-Hurler polydystrophy, involving a deficiency of phospho-N-acetylglucosamninyl transferase activity, are also genetic diseases involving defective oligosaccharide biosynthesis (Kornfeld, 1986. Clin. Invest. 77:1-6).
Alterations in the expression of terminal sialic acid residues on glycoconjugates are common phenomena in oncogenic transformation (Kaneko, 1996; Nicholson, 1982; Roth, 1993; Schirrmacher, 1982; Varki, 1993). Increased cell-surface sialylation has been implicated in invasivity (Collard, 1987), tumor cell-mediated platelet aggregation (Bastida, 1987), resistance to T-cell mediated cell death (Workmeister, 1983), adhesion to endothelial cells and extracellular matrices (Dennis, 1982), and metastatic potential (Passanti, 1988). Studies have shown a correlation between increased terminal sialylation of cell-surface glycoproteins and both the metastatic and invasive potential of a variety of tumors (Collard, 1987; Nicholson, 1982; Passanti, 1988, Varki, 1993). It has also been reported that terminal sialylation of glycoproteins found in human chronic myelogenous leukemia K562 cells increases their resistance to T-cell-mediated cell lysis (Workmeister, 1987).
At least ten distinct enzymes are known to transfer sialic acid to the termini of the oligosaccharide moieties of glycosphingolipids and glycoproteins, termed sialyltransferases. These enzymes comprise a structurally related family of molecules that display substrate specificity, tissue specificity, and are developmentally regulated (Kitagawa, 1994). There are at least two sialyltransferases which transfer sialic acid to the nonreducing termini of sugar chains of N-linked glycoproteins. One is CMP-NeuAc:Galxcex21,3(4)GlcNAc xcex12,3-sialyltransferase (xcex12,6-ST); another is CMP-NeuAc:Galxcex21,3(4)GlcNAc xcex12,3-sialyltransferase (xcex12,3-ST). These transferases have been shown to be cell-type specific and appear to modulate a variety of important cellular processes. It is currently appreciated by those skilled in the art that alterations in the glycosylation of cell surface molecules involved in invasivity (e.g., gangliosides, growth factor receptors, etc.) may have a distinct effect on the tumorigenic and metastatic potential of tumor cells.
Applicants believed their system would be most stringently tested using a disease model having a high incidence of mortality and a low number of treatment options. Brain cancer represents an extremely aggressive form of cancer which is generally associated with a poor prognosis. Presently, treatment of brain cancer is limited in its efficacy and there is a need in the field for efficient and successful strategies for treating brain cancer. While a number of investigators have used cell lines derived from vertebrate brain tumors to study the expression and regulation of various glycosyltransferase (Demetriou, 1995; Takano, 1994; La Marer, 1992), studies using primary human brain tumor material have been very limited. Shen et al. (1984) reported that serum sialyltransferase, using desialylated fetuin as the acceptor, did not significantly differ from controls in glioma patients. Gornati et al. (1985) found that the sialyltransferase involved in the biosynthesis of GD3 from GM3 ganglioside was altered in meningiomas.
The present application provides a methodology that, in at least one embodiment, involves transfer of a gene encoding a protein having glycosyltransferase activity to a cell derived from a primary tumor or a cell line. Applicants herein provide a methodology provide a method with which a neurological disorder such as brain cancer may be treated by altering expression of a protein having sialyltransferase activity, preferably xcex12,6-ST and/or xcex12,3-ST, within a cell. It is recognized by those skilled in the art that there is a need for methodologies with which to treat such disorders, as there is a lack of effective treatments resulting in the suffering and eventual death of many victims of such diseases. The invention of this application provides reagents and methodologies for treatment of a neurological disorder such as brain cancer.